1. Field
Embodiments relate to a secondary battery.
2. Description of the Related Art
Unlike primary batteries, which cannot be recharged, secondary batteries can be repeatedly charged and discharged. Low capacity secondary batteries that use single battery cells may be used as power sources for various portable electronic devices, e.g., cellular phones or camcorders. High capacity secondary batteries that use tens of battery cells connected to each other in a battery pack may be used as power sources for driving motors, e.g., electric scooters or hybrid electric vehicles (HEV).
Secondary batteries may be classified into different types, e.g., cylindrical and prismatic types. A unit battery includes an electrode assembly having positive and negative electrodes and a separator interposed between the positive and negative electrodes, a case for receiving the electrode assembly, and a cap assembly for sealing the case. Positive and negative electrode terminals may be electrically connected to the electrode assembly and outwardly protrude and extend through the cap assembly.
Additionally, a safety vent may be formed in the cap plate. The safety vent is capable of releasing gas when the internal pressure rises to a predetermined pressure. An electrolyte injection hole may be formed at one side of the cap plate. The electrolyte injection hole provides for a passage for injecting an electrolyte into the case. A ball may be press-fit into the electrolyte injection hole for sealing.